PCI, AGP, and AGP Pro cards and expansion slots have different voltages that affect mechanical compatibility with one another. However PCI cards that are universally keyed are compatible in both 5V and 3.3V slots. AGP and AGP Pro universal cards can plug into any 1.5V and 3.3V AGP and AGP Pro slots. 32-bit PCI Slots and Cards come in 3.3V and 5V options. Below is an illustration of what 32-bit PCI 5V and 3.3V and
slots looks like.

32-bit PCI Slot Voltage Visual Comparison

32-bit PCI Golfinger Voltage Visual Comparison

64-bit PCI Slots and Cards come in 3.3V and 5V options. Below is an illustration of what 64-bit PCI 5V, 3.3V and universal goldfingers
and slots looks like.

64-bit PCI Slot Voltage Visual Comparison

64-bit PCI Golfinger Voltage Visual Comparison

AGP Slots and Cards come in 3.3V and 1.5V options. Below is an illustration of what 32-bit PCI 5V, 3.3V and universal goldfingers
and slots looks like.

AGP Slot Voltage Visual Comparison

AGP Golfinger Voltage Visual Comparison

AGP Pro Slots and Cards come in 3.3V and 1.5V options. Below is an illustration of what 64-bit PCI 5V, 3.3V and universal goldfingers
and slots looks like.

AGP Pro Slot Voltage Visual Comparison

AGP Pro Golfinger Voltage Visual Comparison

Riser Cards for 1U and 2U Rackmount Systems

1U and 2U rackmount systems do not offer enough height for an expansion card to be plugged into the motherboard, unless you use a single or
multi-slot riser card.